Antenna charging is a phenomenon where a conducting electrode, referred to as an antenna, is exposed to charged particles. This may occur during plasma etching or plasma deposition, for example. Exposure to charged particles could cause a charge to be collected on the antenna. The antenna may comprise one or more metallization or silicon layers formed overlying a gate of a semiconductor transistor. If the antenna is connected to an active device, such as the above-described gate, the charging of the antenna could create a potential difference across the gate oxide, for example, which may induce current flow or arcing through the gate oxide. Such arcing or current flow could destroy the gate oxide, which is detrimental to the performance of the associated transistor device.
Silicon-on-insulator technology refers to forming semiconductor devices formed on a substrate of oxide, as opposed to a substrate of silicon. The above-described antenna charging phenomena was believed for some time to not affect silicon-on-insulator technology because the silicon islands below the gate oxide are small. Because of this, any charge that may collect on the antenna would quickly settle into this small silicon region, and thus not allow any significant potential difference to arise across the gate oxide. This contrasts with a conventional device formed on a layer of silicon in which a potential difference could develop across the gate oxide, since charge could flow into the silicon substrate. Recently, investigators have recognized that differential charging in which potential charges develop between more than one “antenna” can lead to a potential difference across a portion of a semiconductor device, for example the gate oxide of a silicon-on-insulator device. These antennas refer to antennas that would be connected to the various active portions of the transistor (gate, source, drain). Thus the problem of antenna charging remains in silicon-on-insulator devices.
Techniques used in non-silicon-on-insulator devices to address this problem have involved electrically connecting the charging electrode to the silicon substrate of the semiconductor device through a diode. This allowed the charge developed on the antenna to dissipate to the substrate of the semiconductor device. However, this approach is not applicable to silicon on insulator devices because there is no path to a silicon substrate, due to the oxide layer overlying the substrate.